linux-kernel - Re: [PATCH 1/3] hwmon: spd5118: Do not fail resume on temporary I2C errors

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Message-ID: <2740c3ab-7cb0-4931-81a2-30b85e8615f9@roeck-us.net>
Date: Tue, 13 Jan 2026 15:46:58 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: TINSAE TADESSE <tinsaetadesse2015@...il.com>
Cc: linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] hwmon: spd5118: Do not fail resume on temporary I2C
 errors

On 1/13/26 11:15, TINSAE TADESSE wrote:
> On Mon, Jan 12, 2026 at 7:30 PM Guenter Roeck <linux@...ck-us.net> wrote:
>>
>> On 1/10/26 09:19, Tinsae Tadesse wrote:
>>> SPD5118 DDR5 temperature sensors may be temporarily unavailable
>>> during s2idle resume. Ignore temporary -ENXIO and -EIO errors during resume and allow
>>> register synchronization to be retried later.
>>>
>>> Signed-off-by: Tinsae Tadesse <tinsaetadesse2015@...il.com>
>>> ---
>>>    drivers/hwmon/spd5118.c | 8 +++++++-
>>>    1 file changed, 7 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/hwmon/spd5118.c b/drivers/hwmon/spd5118.c
>>> index 5da44571b6a0..ec9f14f6e0df 100644
>>> --- a/drivers/hwmon/spd5118.c
>>> +++ b/drivers/hwmon/spd5118.c
>>> @@ -512,9 +512,15 @@ static int spd5118_resume(struct device *dev)
>>>    {
>>>        struct spd5118_data *data = dev_get_drvdata(dev);
>>>        struct regmap *regmap = data->regmap;
>>> +     int ret;
>>>
>>>        regcache_cache_only(regmap, false);
>>> -     return regcache_sync(regmap);
>>> +     ret = regcache_sync(regmap);
>>> +     if(ret == -ENXIO || ret == -EIO) {
>>> +             dev_warn(dev, "SPD hub not responding on resume (%d), deferring init\n", ret);
>>> +             return 0;
>>> +     }
>>> +     return ret;
>>>    }
>>>
>>>    static DEFINE_SIMPLE_DEV_PM_OPS(spd5118_pm_ops, spd5118_suspend, spd5118_resume);
>>
>>
>> Based on the subsequent exchange, this is not the appropriate solution.
>> The problem is that the i2c controller suspends too early. It should suspend
>> later instead. Alternatively, this driver should suspend early, but it does
>> not look like respective PM operations are available.
>>
>> I would suggest to try replacing DEFINE_SIMPLE_DEV_PM_OPS() in drivers/i2c/busses/i2c-i801.c
>> with SET_LATE_SYSTEM_SLEEP_PM_OPS() or similar.
>>
>> Guenter
>>
> 
> Hi Guenter,
> 
> I tested changing the i801 SMBus controller to use
> SET_LATE_SYSTEM_SLEEP_PM_OPS() instead of
> DEFINE_SIMPLE_DEV_PM_OPS() as a diagnostic experiment. With this
> change, spd5118 resume failures (-ENXIO)
> still persist, suggesting PM ordering alone is insufficient and other
> firmware interactions are involved.

How about the problem in the suspend function ? Is that also still seen ?

Also, the subject talks about -EIO. Is that still seen ?

Either case, can you enable debug logs for the i801 driver ?
It should generate log entries when it reports errors.

Thanks,
Guenter